Item 4. All Possibilities Pursued

Throughout the 1970s, all of Toyota's engineering departments and in particular the Development Planning Department made every effort to develop technologies for cleaner emissions. Emissions controls were basically uncharted territory and presented issues that could not be resolved through extensions of existing technologies.

Three components of emissions?CO, HC, and nitrogen oxide (NOX)-are generated in inverse amounts depending on the ratio of the mixture of air to gasoline, and reducing all three simultaneously seemed to be an insurmountable problem.

In addition, introducing to the marketplace vehicles with emissions controls as commercial products also required finding ways to overcome accompanying issues such as reduced engine output, lower fuel efficiency, decreased driving performance, the degradation of countermeasure components and increased costs.

Toyota's engineering departments pursued all possibilities to overcome these numerous problems. They first developed an emissions control system that used a catalyst. Using a catalyst would allow engine performance to be maintained at previous levels to the greatest possible extent while the catalyst cleaned the emissions. The system combined air injection1 for re-combustion of CO and HC in the emissions and an exhaust gas recirculator to reduce NOx by recirculating some of the emissions through the intake with a catalytic converter.2

Toyota also conducted research on improving engines through combustion control. It was able to improve fuel efficiency by using a lean combustion method that maintained stable combustion of a uniform and lean mixture and controlled the generation of CO, HC, and NOx during the combustion phase. But the lean fuel-air mixture worsened ignition performance and decreased the stability of combustion, entailing significant problems during development and practical application. At the end of 1972, Toyota also introduced compound vortex-controlled combustion (CVCC) technology as a type of combustion control developed by Honda Motor Co., Ltd. and continued to research and improve lean combustion technology. Toyota also actively advanced its development of gas turbine engines and rotary engines, for which it began research in 1964 and 1967, respectively, as well as of electric and other types of vehicles.

As emissions controls were being pursued as such through all types of systems, a decision was made at the end of 1971 that the use of catalysts would form the main approach to controlling emissions. This decision was made based on comprehensive considerations including the cleaning of emissions as well as fuel efficiency, driving performance, serviceability, and cost.

Even though this policy was adopted, the engineering departments still had numerous problems to overcome. Catalysts were sensitive to external conditions, and, unlike how they were used in devices in the chemical industry, using them in vehicles meant that they would be used in highly variable environments. In addition, the catalyst manufacturer that supplied Toyota prohibited Toyota from analyzing the samples provided and tested, and Toyota only learned of the performance of sample catalysts after full analysis by the manufacturer.

Toyota determined that this method of development was not suitable for the pace of development that it needed and decided to develop catalysts in-house. In cooperation with Toyota Central Research & Development Labs, Inc., the Catalysts Development Group was established in the Engineering Department No. 5 in February 1971. The group immediately began testing 5,000 different types of catalysts. Engineers in charge of engines and those in charge of catalysts communicated constantly to tackle the monumental task of achieving optimal compatibility between the emissions subjected to the catalysts and catalytic cleaning performance.

Improving reliability was also a difficult issue. The development and testing periods were short, and it was necessary to develop the needed system for all vehicles in a short period, so a failure mode and effect analysis method3 -a reliability method used in the U.S. aerospace and other industries-was adopted. Starting in the design stage, not only were components examined in detail, each part was also carefully considered and tested in terms of how various problems and variations originating during production could affect the reliability of the emissions purification system, and countermeasures were implemented as needed starting with the key components.

As for production, to be able to achieve mass production of emissions control components with limited lead time, the Special Components Manufacturing Planning Department was established in July 1972. The department immediately went to work on procedures to commercialize emissions control components and on preparations for production. Toyota adopted a policy of manufacturing the components internally until their designs were stabilized to avoid imposing risks on suppliers as a result of changes to the components, which were still under development and were subject to modification at any time. Even so, selecting the right quality of material for the container of the catalytic converter that could withstand extreme changes in temperature and coming up with a mass production method was an effort wrought with considerable difficulties, given that it involved a field in which Toyota had no experience.

When manufacturing new products, in some cases the products are discontinued within a short period and it is not possible to recover the initial investment. But in this case, it would not do to hesitate because of this concern. In December 1972, Toyota representatives visited producer countries of the platinum and palladium to be used as the catalysts and signed direct purchase agreements.

A ground-breaking ceremony was held at the site of the Shimoyama Plant in April 19736, and construction of Plant No. 1 was completed in August 1974. Because of changes in circumstances following the oil crisis (that began in 1973), however, the start of operations at the plant was postponed from August 1974 to March 1975. During this period, emissions control components were produced at the Miyoshi Plant, and the Shimoyama Plant served as a backup. The Shimoyama Plant began producing components for the M engine in March 1975.

A secondary air supply device. The device supplies air (referred to as secondary air) to the exhaust system in order to re-combust CO and HC.

2

A device that contains a catalyst for purifying exhaust emissions.

3

A method of analyzing failure modes of constituent elements and their effects on upper-level items in order to identify incomplete designs and potential weaknesses. (Society of Automotive Engineers of Japan, Japanese-English Automotive Dictionary) The method quantitatively analyzes the effects of a single breakdown (defect, imperfect function, failure) of a subsystem on the reliability, maintainability, and safety of the entire system, sets priorities based on the importance of the identified issues, and implements advance countermeasures.

4

The current address of the Shimoyama Plant is 1 Shimoyama, Uchikoshi-cho, Miyoshi City, Aichi Prefecture.